[0001] The present invention relates to a novel thermoplastic resin composition which shows
excellent flowability during molding and gives molded articles having excellent impact
resistance and a high heat distortion temperature.
[0002] Resin compositions comprising a polyarylate and a poly(alkylene-phenylene ester)
are known, which can give molded articles having an excellent balance between heat
distortion resistance and chemical resistance. However, these compositions have a
drawback that their impact resistance is generally low and this poses practical problems.
[0003] As an expedient for improving the poor impact resistance, incorporation of a glycidyl
ester group-containing copolymer produced from an a-olefin and a glycidyl ester of
an a,;8-unsaturated acid into a composition of the above kind is disclosed in JP-A-61-26657.
(The term "JP-A" as used herein means an "unexamined published Japanese patent application".)
This expedient, however, is defective in that almost no improvement is attained in
notched Izod impact strength at a low temperature (-30 ° C), although the room-temperature
notched Izod impact strength of the composition is surely improved. In addition, the
thus- modified composition has a practically serious problem that it shows significantly
impaired flowability during molding.
[0004] The object of the present invention is to provide a resin composition having exceedingly
good impact resistance, particularly, low-temperature Izod impact strength, as well
as good flowability for molding.
[0005] This object could, be achieved by the present invention on the basis of the finding
that a novel resin composition comprising a polyarylate, a poly(alkylene-phenylene
ester), and a specific chemically modified polyolefin copolymer has greatly improved
impact resistance, in particular, low-temperature Izod impact strength, while retaining
good flowability for molding.
[0006] According to the present invention, a thermoplastic resin composition is provided
which comprises 100 parts by weight of the following component (A) and from 1 to 50
parts by weight of the following component (B):
(A) a resin component comprising
(i) from 10 to 90% by weight of a polyarylate produced by polymerizing a dihydric
phenol represented by formula (I)

wherein X is one member selected from the group consisting of O, S, S02, CO, a C,-C2o alkylene group, and a Cs-C2o alkylidene group and Ri, R2, R3, R4, R1', R2', R3', and R4' each is one member selected from the group consisting of hydrogen atom, a halogen
atom, and a Ci-C4 hydrocarbon group, or a derivative of the dihydric phenol, with
an aromatic dicarboxylic acid or a derivative thereof and
(ii) from 90 to 10% by weight of a poly(alkylene-phenylene ester);
(B) a chemically modified polyolefin copolymer having a structural unit containing
at least one amide group and at least one glycidyloxy or glycidyl group, the number
of the structural unit contained in the copolymer being one per from 4 to 5,000 carbon
atoms of the polyolefin moiety.
[0007] Resin component (A) contained in the resin composition of the present invention comprises
(i) a polyarylate and (ii) a poly(alkylene-phenylene ester).
[0008] This polyarylate (i) may be synthesized from a dihydric phenol or derivative thereof
and an aromatic dicarboxylic acid or derivative thereof through a polycondensation
reaction, for example, an interfacial polycondensation, a solution polymerization,
a molten-state polymerization.
[0009] As the dihydric phenol, any of various dihydric phenols represented by formula (I)

wherein X is one member selected from the group consisting of 0, S, S0
2, CO, a C,-C
2o alkylene group, and a Cs-C
2o alkylidene group and Ri, R
2, R
3, R
4, R
1', R
2', R
3', and R
4' each is one member selected from the group consisting of hydrogen atom, a halogen
atom, and a C, -C
4 hydrocarbon group.
[0010] As shown in formula (I), the dihydric phenol may be substituted, preferably with
a halogen atoms, such as chlorine, bromine atoms, and a C
1-C
4 alkyl group.
[0011] Examples of the dihydric phenol include 2,2-bis(4'-hydroxyphenyl)propane (also called
bisphenol A), bis(4-hydroxyphenyl)methane, bis(4-hydroxy-3,5-dimethylphenyl)methane,
bis(4-hydroxy-3,5-dichlorophenyl)methane, 1,1-bis(4'-hydroxyphenyl)ethane, bis(4-hydroxyphenyl)cyclohexylmethane,
1,1-bis(4'-hydroxyphenyl)-1-phenylethane, 4,4'-dihydroxydiphenyl ether, bis(4-hydroxy-3,5-dimethylphenyl)ether,
bis-(4-hydroxyphenyl) sulfone, bis(4-hydroxy-3,5-dimethylphenyl)sulfone, 4,4'-dihydroxybenzophenone,
and 2,2- bis(4'-hydroxy-3',5'-dimethylphenyl)propane.
[0012] Derivatives of such dihydric phenols include alkali metal salts and diacetates thereof.
These dihydric phenols and derivatives thereof may be used alone or in combination
of two or more thereof. If required and necessary, a dihydroxy compound such as, for
example, 4,4'-dihydroxybiphenyl, hydroquinone, resorcinol, or 2,6-dihydroxynaphthalene
may be used in a small amount along with the dihydric phenol or its derivative described
above.
[0013] As the aromatic dicarboxylic acid for use in producing the polyarylate to be contained
in the composition of the present invention, any of various kinds of aromatic dicarboxylic
acids which may be substituted by a halogen atom, such as chlorine, bromine atom,
or a C
1-C
4 alkyl group, can be used. Examples thereof include isophthalic acid, terephthalic
acid, (diphenyl ether)-4,4'-dicarboxylic acid, benzophenone-4,4'-dicarboxylic acid,
and naphthalene-2,6-dicarboxylic acid.
[0014] Particularly preferred of these aromatic dicarboxylic acids are isophthalic acid
and terephthalic acid. Derivatives of those aromatic dicarboxylic acids include dichlorides
thereof and products of alkylation or arylation thereof. Such aromatic dicarboxylic
acids and derivatives thereof may be used alone or in combination of two or more thereof.
[0015] From the dihydric phenol or its derivative and the aromatic dicarboxylic acid or
its derivative, a polyarylate to be employed in the present invention can be produced
by any of various polymerization methods such as, for example, interfacial polycondensation,
solution polymerization, and molten-state polymerization. It is, however, preferable
that the polyarylate thus produced have a solution viscosity in the range of from
0.2 to 1.5 (chloroform solution, 30 ° C) in terms of intrinsic viscosity. Use of polyarylates
having viscosities outside this range tends to give resin compositions having impaired
impact resistance, heat distortion resistance, moldability, or other properties.
[0016] The poly(alkylene-phenylene ester) (ii) to be employed in the resin composition of
the present invention may be produced by any of such polymerization methods as interfacial
polymerization, solution polymerization and molten-state polymerization. This poly(alkylene-phenylene
ester) is represented by formula (IV)

wherein R
11 R12, Ri3, and R
14 each is one member selected from the group consisting of hydrogen atom, an alkyl
group, an alkoxy group, an alkyl ester group, cyano group, amino group, sulfonic acid
group, nitro group, and phenoxy group and m is an integer of from 1 to 10.
[0017] Specific examples of the poly(alkylene-phenylene ester) to be contained in the composition
of the present invention include such polyesters as poly(ethylene terephthalate),
poly(ethylene isophthalate), poly-(trimethylene terephthalate), poly(trimethylene
isophthalate), poly(butylene terephthalate), and poly(butylene isophthalate). These
polyesters may be used alone or in combinations of two or more thereof. Preferred
of these are poly(ethylene terephthalate) (PET) and poly(butylene terephthalate) (PBT).
[0018] It is preferred that the poly(alkylene-phenylene ester) have an intrinsic viscosity
in the range of from 0.3 to 1.5 dl/g, especially from 0.4 to 1.2 dl/g (phenol/tetrachloroethane
= 6/4 (by weight), 25 C). Intrinsic viscosities outside the above range are not preferred
in that use of polyesters having intrinsic viscosities below 0.3 dl/g results in resin
compositions having insufficient impact strengths, while polyesters having intrinsic
viscosities exceeding 1.5 dl/g tend to give resin compositions showing poor flowability
during molding.
[0019] The chemically modified polyolefin copolymer (B) contained in the resin composition
of the present invention has a structural unit containing at least one amide group
and at least one glycidyloxy or glycidyl group, with the number of this structural
unit contained in the chemically modified copolymer being one per from 4 to 5,000
carbon atoms of the polyolefin moiety. A particularly preferred example of this chemically
modified polyolefin copolymer is one having a glycidyl ether group-containing structural
unit represented by formula (II)

wherein Ar represents an aromatic hydrocarbon group having from 6 to 23 carbon atoms
and containing at least one glycidyloxy group and R represents hydrogen atom or methyl
group), the number of the structural unit of formula (II) contained in the chemically
modified copolymer being one per from 4 to 5,000 carbon atoms of the polyolefin moiety.
[0020] Examples of the polyolefin in the modified polyolefin copolymer to be incorporated
in the resin composition of the present invention include olefin homopolymers such
as polyethylene, polypropylene, and poly(butene-1) and olefin copolymers such as ethylene-propylene
copolymers, ethylene-propylene-diene copolymers, ethylene-vinyl acetate copolymers,
and ethylene-acrylic ester copolymers. These polyolefins may be used alone or in combination
of two or more thereof. Particularly preferred of these are ethylene-propylene copolymers
and ethylene-propylene-diene copolymers.
[0021] Examples of the dienes include conjugated dienes such as butadiene, isoprene, chloroprene,
and phenylpropadiene, cyclic dienes such as cyclopentadiene, 1,5-norbornadiene, 1,3-cyclohexadiene,
1,4-cyclohexadiene, 1,5-cyclooctadiene, and 1,3-cyclooctadiene, and a,,,,-nonconjugated
dienes. These may be used alone or in combination of two or more thereof.
[0022] In producing those olefin copolymers, one or more unsaturated monomers copolymerizable
with the comonomers may be copolymerized therewith. Examples of the unsaturated monomers
include vinyl ethers, vinyl esters such as vinyl acetate and vinyl propionate, acrylic
or methacrylic esters such as methyl, ethyl, propyl, and butyl acrylates or methacrylates,
acrylonitrile, and styrene.
[0023] The glycidyl ether group-containing structural unit represented by formula (II) given
above may be incorporated by the radical addition or copolymerization of a glycidyl
ether group-containing modifier represented by formula (V)

where AI represents an aromatic hydrocarbon group having from 6 to 23 carbon atoms
and contains at least one glycidyloxy group and R represents hydrogen atom or methyl
group to or with the polyolefin described above. Such modifiers can be produced by
the method described in JP-B-2-051550. (The term "JP-B" as used herein means an examined
Japanese patent publication".)
[0024] One particularly preferred example of the modifier represented by formula (V) is
a compound shown by formula (VI).

[0025] The chemically modified polyolefin copolymer (B) to be incorporated in the resin
composition of the present invention should have a structural unit containing at least
one amide group and at least one glycidyloxy or glycidyl group, with the number of
this structural unit contained in the modified copolymer being one per from 4 to 5,000
carbon atoms, preferably from 50 to 3,000 carbon atoms, of the polyolefin described
above. It is preferable that the above structural unit be a glycidyl ether group-containing
structural unit represented by formula (II) given hereinabove. Use of a modified polyolefin
copolymer which does not satisfy the above requirement is disadvantageous in that
a sufficient improvement in impact resistance cannot be attained or the resulting
resin composition shows impaired flowabilty during molding.
[0026] Preferred examples of modified polyolefin copolymer (B) include ethylene-propylene
or ethylene-propylene-diene copolymers onto which a glycidyl ether group-containing
structural unit shown by formula (III)

has been grafted.
[0027] It is preferable that modified polyolefin copolymer (B) usually have a melt index
(MI) in the range of from 0.01 to 100 g/10 min. Melt indexes outside this range are
not preferred because the impact resistance- improving effect of such copolymers tends
to be insufficient. The melt index values herein mean those measured in accordance
with ASTM D-1238 at 230 ° C.
[0028] Production methods for chemically modified polyolefin copolymer (B) are not particularly
limited. For example, chemically modified polyolefin copolymer (B) may be obtained
by melt-mixing a polyolefin with the above-described modifier using any of various
blenders such as an extruder, heated rollers, Brabender and Banbury mixer. Alternatively,
chemically modified polyolefin copolymer (B) may be synthesized by copolymerizing
one or more olefin monomers with the above-described modifier by means of a generally
employed polymerization method such as, for example, radical polymerization, cationic
polymerization, anionic polymerization, or coordination polymerization.
[0029] The amount of the above-described chemically modified polyolefin copolymer (B) incorporated
in the resin composition of the present invention is from 1 to 50 parts by weight,
preferably from 3 to 30 parts by weight, per 100 parts by weight of resin blend (A)
consisting of from 10 to 90% by weight of polyarylate (i) and from 90 to 10% by weight
of poly(alkylene-phenylene ester) (ii). If the incorporated amount of chemically modified
polyolefin copolymer (B) is below 1 part by weight, a sufficient improvement in impact
resistance cannot be attained. If the amount thereof exceeds 50 parts by weight, the
resin composition may have poor heat distortion resistance and show poor flowability
during molding.
[0030] In producing the thermoplastic resin composition of the present invention, methods
for blending components (A) and (B) are not particularly limited. However, a melt
mixing method is most preferably used, in which components (A) and (B) may be melt-mixed
by means of any of various blenders such as, for example, an extruder, heated rollers,
Brabender and Banbury mixer.
[0031] Various additives may be optionally incorporated into the resin composition of the
present invention to impart thereto one or more functions not originally possessed
by the composition. Examples of the additives include lubricants such as waxes, stabilizers,
e.g. of the phosphorus-containing or phenolic type, ultraviolet absorbers, pigments,
flame retardants, plasticizers, inorganic fillers, and reinforcing fibers.
[0032] The thermoplastic resin composition of the present invention shows excellent flowability
during molding and molded articles obtained from the composition have excellent impact
resistance and a high heat distortion temperature. The resin composition of the present
invention, therefore, is suitable as a molding material for producing, for example,
automotive parts, machine parts, electrical or electronic parts, and other molded
articles.
[0033] The present invention will be illustrated in more detail with reference to the following
examples, but the invention is not construed as being limited thereto.
1. Production of Resin Compositions
EXAMPLES 1 TO 14
[0034] The polyarylate, poly(alkylene-phenylene ester)s, and modified polyolefin copolymers
each specified below were blended according to the formulations given in Table 1.
Each component was extruded at 270 ° C with a twin-screw extruder (LABOTEX 30, manufactured
by The Japan Steel Works, Ltd.) to produce a resin composition in pellet form.
Polyarylate:
[0035] Bisphenol A and a mixture of isophthaloyl dichloride and terephthaloyl dichloride
(8/2 by mol) were subjected to polycondensation reaction in a molar ratio of 1:1,
thereby preparing a polyarylate (intrinsic viscosity, 0.63).
Poly(Alkylene-Phenylene Ester)s:
[0036] Poly(ethylene terephthalate) (Kurapet KD226R, manufactured by Kuraray Co., Ltd.,
Japan) and poly-(butylene terephthalate) (Valox 310, manufactured by General Electric
Co.) were used.
Chemically Modified Polyolefin Copolymer (B-1):
[0037] To 100 parts by weight of an ethylene-propylene-diene copolymer (EP 57P, manufactured
by Japan Synthetic Rubber Co., Ltd.) having a melt index of 0.4 g/10 min as measured
at 230 ° C under a load of 2.2 kg were added, at ambient temperature, 3 parts by weight
of a glycidyl ether group-containing modifier shown by formula (VI)

and 0.16 part by weight of a,a'-bis(t-butylperoxy-m-isopropyl)benzene (Perbutyl P,
manufactured by Nippon Oil & Fats Co., Ltd., Japan). This mixture was extruded at
250 ° C with a twin-screw extruder (TEX 44, manufactured by The Japan Steel Works,
Ltd.), thereby allowing the modifier to react with the copolymer. Thus, a chemically
modified polyolefin copolymer (B-1) in pellet form was obtained.
[0038] The grafted amount of the modifier was determined by crushing pellets of the chemically
modified copolymer, washing the resulting powder five times with methylene chloride
to remove the unreacted modifier and homopolymers of the modifier, and then subjecting
the washed powder to IR spectroscopy and elemental analysis for nitrogen atom. As
a result, the grafted modifier amount was found to be 1.9% by weight based on 100%
by weight of a modified polyolefin copolymer.
[0039] Chemically modified polyolefin copolymer B-1 obtained above in pellet form had a
melt index as measured at 230 °C of 0.5 g/10 min, and was also found to have one structural
unit containing a glycidyl ether group as shown by formula (II), per 972 carbon atoms
of the polyolefin moiety.
Chemically Modified Polyolefin Copolymer (B-2):
[0040] To 100 parts by weight of an ethylene-propylene-diene copolymer (EP 57P, manufactured
by Japan Synthetic Rubber Co., Ltd.) having a melt index of 0.4 g/10 min as measured
at 230 ° C under a load of 2.2 kg were added, at ambient temperature, 6 parts by weight
of a glycidyl ether group-containing modifier shown by formula (VI) given above and
0.16 part by weight of a,a'-bis(t-butylperoxy-m-isopropyl)benzene (Perbutyl P, manufactured
by Nippon Oil & Fats Co., Ltd.). This mixture was extruded at 250 ° C with a twin-screw
extruder (TEX 44, manufactured by The Japan Steel Works, Ltd.), thereby allowing the
modifier to react with the copolymer. Thus, a chemically modified polyolefin copolymer
(B-2) in pellet form was obtained.
[0041] The grafted amount of the modifier was determined by crushing pellets of the chemically
modified copolymer, washing the resulting powder five times with methylene chloride
to remove the unreacted modifier and homopolymers of the modifier, and then subjecting
the washed powder to IR spectroscopy and elemental analysis for nitrogen atom. As
a result, the grafted modifier amount was found to be 3.8% by weight.
[0042] Chemically modified polyolefin copolymer B-2 obtained above in pellet form had a
melt index as measured at 230 ° C of 0.4 g/10 min, and was also found to have one
structural unit containing a glycidyl ether group and shown by formula (II), per 486
carbon atoms of the polyolefin moiety.
Chemically Modified Polyolefin Copolymer (B-3):
[0043] To 100 parts by weight of an ethylene-propylene copolymer (EP 02P, manufactured by
Japan Synthetic Rubber Co., Ltd.) having a melt index of 3.2 g/10 min as measured
at 230 ° C under a load of 2.2 kg were added, at ambient temperature, 3 parts by weight
of a glycidyl ether group-containing modifier shown by formula (VI) given above and
0.16 part by weight of a,a'-bis(t-butylperoxy-m-isopropyl)benzene (Perbutyl P, manufactured
by Nippon Oil & Fats Co., Ltd.). This mixture was extruded at 250 C with a twin-screw
extruder (TEX 44, manufactured by The Japan Steel Works, Ltd.), thereby allowing the
modifier to react with the copolymer. Thus, a chemically modified polyolefin copolymer
(B-3) in pellet form was obtained.
[0044] The grafted amount of the modifier was determined by crushing pellets of the chemically
modified copolymer, washing the resulting powder five times with methylene chloride
to remove the unreacted modifier and homopolymers of the modifier, and then subjecting
the washed powder to IR spectroscopy and elemental analysis for nitrogen atom. As
a result, the grafted modifier amount was found to be 2.4% by weight.
[0045] Chemically modified polyolefin copolymer B-3 obtained above in pellet form had a
melt index as measured at 230 ° C of 4.3 g/10 min, and was also found to have one
structural unit containing a glycidyl ether group and shown by formula (II), per 758
carbon atoms of the polyolefin moiety.
Chemically Modified Polyolefin Copolymer (B-4):
[0046] To 100 parts by weight of an ethylene-propylene copolymer (EP 02P, manufactured by
Japan Synthetic Rubber Co., Ltd.) having a melt index of 3.2 g/10 min as measured
at 230 ° C under a load of 2.2 kg were added, at ambient temperature, 6 parts by weight
of a glycidyl ether group-containing modifier shown by formula (VI) given above and
0.16 part by weight of a,a'-bis(t-butylperoxy-m-isopropyl)benzene (Perbutyl P, manufactured
by Nippon Oil & Fats Co., Ltd.). This mixture was extruded at 250 °C with a twin-screw
extruder (TEX 44, manufactured by The Japan Steel Works, Ltd.), thereby allowing the
modifier to react with the copolymer. Thus, a chemically modified polyolefin copolymer
(B-4) in pellet form was obtained.
[0047] The grafted amount of the modifier was determined by crushing pellets of the chemically
modified copolymer, washing the resulting powder five times with methylene chloride
to remove the unreacted modifier and homopolymers of the modifier, and then subjecting
the washed powder to IR spectroscopy and elemental analysis for nitrogen atom. As
a result, the grafted modifier amount was found to be 4.8% by weight.
[0048] Chemically modified polyolefin copolymer B-4 obtained above in pellet form had a
melt index as measured at 230°C of 3.8 g/10 min, and was also found to have one structural
unit containing a glycidyl ether group and shown by formula (II), per 370 carbon atoms
of the polyolefin moiety.
COMPARATIVE EXAMPLES 1 TO 9
[0049] The polyarylate and poly(alkylene terephthalate)s used in Examples 1 to 14 and the
glycidyl ester group-containing copolymer as specified below were blended according
to the formulations given in Table 1. Each blend was extruded at 270 ° C with a twin-screw
extruder (LABOTEX 30, manufactured by The Japan Steel Works, Ltd.) to produce a resin
composition in pellet form.
Glycidyl Ester Group-Containing Copolymer (B-5):
[0050] Ethylene/glycidyl methacrylate copolymer (Bondfast E, manufactured by Sumitomo Chemical
Co., Ltd., Japan) was used.
2. Measurements of Izod Impact Strength and Spiral Flow Length
[0051] Each of the pelleted resin compositions prepared in section 1 above was dried under
a reduced pressure at 120 °C for 15 hours and then injection-molded into test pieces.
Each of the test piece samples of Examples 1 to 14 and Comparative Examples 1 to 9
was evaluated for Izod impact strength and spiral flow length according to the following
methods.
Izod Impact Strength:
[0052] Measurement was made in accordance with ASTM D-256 (with 1/4-inch notch; ambient
temperatures, 23°C and -30 °C).
Spiral Flow:
[0053] Using a 3.5-ounce injection-molding machine (IS 80EPN, manufactured by Toshiba Machine
Co., Ltd., Japan), each sample was injected into a spiral mold having a gate section
of 3 mm x 3 mm, width of 4 mm, and thickness of 3 mm under conditions of a cylinder
temperature of 280 °C, injection pressure of 120 kg/cm
2 (gauge pressure), and mold temperature of 80 ° C. The length of the injected sample
that flowed along the mold spiral was measured.

[0054] As apparent from Table 1, injection-molded samples obtained from the resin compositions
of the present invention in which chemically modified polyolefin copolymers B-1 to
B-4 had been incorporated not only had high Izod impact strengths but showed long
spiral flow lengths, i.e., excellent flowability for molding (Examples 1 to 14).
[0055] In contrast, molded samples obtained from the compositions consisting only of a polyarylate
and either poly(ethylene terephthalate) or poly(butylene terephthalate) had low Izod
impact strengths (Comparative Examples 1 to 3 and 7). Further, the compositions containing
a chemically modified polyolefin copolymer in amounts outside the range specified
hereinabove and the compositions containing glycidyl ester group-containing copolymer
B-5 in place of a chemically modified polyolefin copolymer failed to give molded samples
which simultaneously had both high impact resistance and good flowability for molding
(Comparative Examples 4 to 6, 8, and 9).
[0056] It is a surprising fact that, as demonstrated above, the compositions of the present
invention produced by incorporating the specific modified polyolefin copolymer into
blends of a polyarylate and a poly(alkylene terephthalate) exhibited excellent properties.
[0057] As described above in detail, when the resin composition of the present invention
is used as a plastic molding material by any of various molding techniques such as
injection molding, extrusion, blow molding, and compression molding, plastic molded
articles having excellent impact resistance can be obtained with good flowability
for molding which are suited for use as various parts including automotive, machine,
and electrical or electronic parts.